JP2005184911A - Motor input and output factor correcting device of wheel-independent drive electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize controlling of the drive force of each wheel as aimed, by correcting the input and output characteristics of an electric motor for individually driving the respective wheels so as to agree with actual characteristics. <P>SOLUTION: A motor input and output factor correcting device of a wheel independent drive electric automobile travels a vehicle by driving front wheels at a step S2, while deciding that a straight travel is instructed based on a steering angle θ at a step S1. When it is decided that yaw rate ϕ is generated in step S3 even though a straight travel has been instructed, the drive force difference Tm of the left and the right front wheels of its cause is calculated at steps S4, S5, and the motor drive force of the vehicle turning direction inside wheel is increased by Tm/2, based on the motor input command value at the Tm calculating time in steps S6, S7. Motor input and output factors are obtained so that the motor drive force of the vehicle turning direction outside wheel is lowered by Tm/2. They are set as the motor input and output factors after correction, with respect to the electric motor of the front wheel at the corresponding side. In steps S7-S10, similar process is performed by the rear wheel drive, and the input and output factors are corrected for the electric motors of the left and right rear wheels, as well. At steps S13-S20, a constant speed travel made to be conducted by the front wheel drive and by the rear wheel drive. The input and output factors of the front and rear wheel electric motors are corrected, from the difference in the motor output (torque) target values of the front and rear wheels, at this time. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  According to the present invention, the variation characteristic (motor input / output coefficient) of the output value (output target value) with respect to the input command value of the electric motor varies with respect to the wheel independent drive electric vehicle in which the wheel is independently driven by each electric motor. The present invention relates to a technique for correcting motor input / output coefficients so that the driving force of each wheel can be controlled as intended.

As a wheel independent drive electric vehicle which drives each wheel independently by an electric motor, a vehicle as described in Patent Document 1 is known.
Japanese Utility Model Publication No.59-141405

  The wheel-independent drive electric vehicle described in Patent Document 1 corresponds to a target acceleration commanded by a driver using an accelerator pedal, a traveling direction such as a steering direction commanded by a driver using a steering wheel, and a traveling state such as a vehicle speed. By calculating the torque command value of the electric motor related to each wheel and driving and controlling the motor of each wheel, the vehicle travels straight and turns, and also improves the running performance of the vehicle.

However, the conventional wheel-independent drive electric vehicle as described above has the following problems.
In other words, when the electric motor cannot output an output value such as an accurate torque corresponding to the input command value due to variations in the motor input / output coefficient representing the change characteristics of the output value (output target value) relative to the input command value. The output value is greatly deviated from the output target value, and the driving force of each wheel cannot be controlled as intended.
If the driving force of the left and right wheels cannot be controlled as intended, the vehicle cannot travel straight or turn as the steering operation of the driver, and if the driving force of the front and rear wheels cannot be controlled as intended, The driving force may not be properly distributed between the front and rear wheels, so that the target running performance cannot be realized, or electric energy is wasted, leading to deterioration of power consumption.

  The present invention is used to obtain an input command value from an output target value even if the motor input / output coefficient representing the change characteristic of the output value (output target value) with respect to the input command value of the electric motor has variations. By correcting the motor input / output coefficient so that it is closer to the actual value, the driving force of each wheel can be controlled as intended, so that problems such as the above-mentioned straightness and turning performance, deterioration of running performance and waste of power can be achieved. The purpose is to solve the problem.

In order to solve the former problem, a motor input / output coefficient correcting device for a wheel independent drive electric vehicle according to the present invention is configured as described in claim 1.
First, to explain the wheel independent drive electric vehicle which is the premise of the present invention,
The left and right wheels are independently driven by individual electric motors, and the input command values of these electric motors are determined from the output target values according to the planned motor input / output coefficients between these input command values and output target values. Is.

In the present invention, for such a wheel independent drive electric vehicle,
Target traveling direction detection means for detecting the target traveling direction of the vehicle from the steering direction input to the steering means of the wheel independent drive electric vehicle;
An actual traveling direction detection means for detecting the actual traveling direction of the wheel independent drive electric vehicle;
Motor input / output coefficient correcting means for correcting the scheduled motor input / output coefficient so that the actual traveling direction approaches the target traveling direction based on the detection results by these means is provided.

In order to solve the latter problem, a motor input / output coefficient correcting device for a wheel independent drive electric vehicle according to the present invention is configured as described in claim 6.
First, to explain the wheel independent drive electric vehicle which is the premise of the present invention,
Front and rear wheels are driven independently by individual electric motors, and the input command value of each electric motor is determined from the output target value according to the expected motor input / output coefficient between these input command value and output target value. Is.

In the present invention, for such a wheel independent drive electric vehicle,
Front wheel drive constant speed traveling means for traveling the wheel independent drive electric vehicle at a constant speed by front wheel drive;
Rear wheel drive constant speed traveling means for causing the wheel independent drive electric vehicle to travel at a constant speed by rear wheel drive under the same conditions and at the same speed;
Based on the front wheel electric motor input command value during constant speed traveling and the rear wheel electric motor input command value during constant speed traveling during front wheel driving constant speed traveling and rear wheel driving constant speed traveling by these means, the front wheel electric motor output target The planned motor input / output coefficient is corrected so that the value and the rear wheel electric motor output target value are between the front wheel electric motor output target value and the rear wheel electric motor output target value based on the planned motor input / output coefficient, respectively. Motor input / output coefficient correcting means is provided.

According to the former invention, between the input command value and the output target value of each electric motor related to the left and right wheels so that the actual traveling direction of the wheel independent drive electric vehicle approaches the target traveling direction of the vehicle detected from the steering direction or the like. Because the motor input / output coefficient that is planned is corrected,
Even if the input / output coefficients of the left and right wheel electric motors are different, the driving force of the left and right wheels can be controlled as desired, and the vehicle can go straight while not steering or turn as desired while steering. Can be achieved.

According to the latter aspect of the present invention, the electric vehicle is driven at a constant speed (front wheel drive constant speed travel) by front wheel drive under the same conditions and at the same speed, and at a constant speed (rear wheel drive constant speed travel) by rear wheel drive. ,
Based on the front wheel electric motor input command value during constant speed driving and the rear wheel electric motor input command value during constant speed driving during the front wheel driving constant speed driving and the rear wheel driving constant speed driving, the front wheel electric motor output target value and The rear wheel electric motor output target value is between the front wheel electric motor output target value and the rear wheel electric motor output target value based on the expected motor input / output coefficient between the input command value and output target value of each electric motor related to the front and rear wheels, respectively. The expected motor input / output coefficient will be corrected to the value of
Even if the front / rear wheel electric motors have different input / output coefficients, the front / rear wheel driving force can be controlled as desired, and the driving performance is not properly distributed between the front / rear wheels to achieve the desired driving performance. It is possible to solve the problem of not being obtained or causing waste of power consumption.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 is a schematic plan view showing a four-wheel independent drive type electric vehicle 1 including a motor input / output coefficient correction device according to an embodiment of the present invention, together with its drive system and steering system.
The electric vehicle 1 includes an electric motor 2FL for driving a left front wheel (not shown), an electric motor 2FR for driving a right front wheel (not shown), an electric motor 2RL for driving a left rear wheel (not shown), and An electric motor 2RR for driving the right rear wheel (not shown) is provided, and the electric vehicle 1 can be driven by individually driving the corresponding wheels by these electric motors 2FL, 2FR, 2RL, 2RR.

The battery 3 is provided as a common power source for the electric motors 2FL, 2FR, 2RL, and 2RR. It is assumed that the motor is driven to generate a motor output (torque) target value.
Each of the motor controllers 4FL, 4FR, 4RL, and 4RR receives a motor input (drive voltage) command value corresponding to the motor output (torque) target value from the control unit 5, and receives the voltage from the battery 3 as the motor input (drive). Voltage) Controls the voltage corresponding to the command value and applies it to the corresponding electric motor 2FL, 2FR, 2RL, 2RR, and the output torque of the motor 2FL, 2FR, 2RL, 2RR matches the above motor output (torque) target value, respectively Shall be allowed to.

In order for the control unit 5 to obtain the motor output (torque) target value of each wheel and the motor input (drive voltage) command value corresponding thereto,
A signal from a steering angle sensor 7 that detects a steering angle θ of a steering wheel 6 that is a steering means;
A signal from the vehicle speed sensor 8 for detecting the vehicle speed VSP;
A signal from a yaw rate sensor 9 for detecting a yaw rate φ, which is a turning angular velocity about a vertical axis passing through the center of gravity of the electric vehicle 1,
A signal from the accelerator opening sensor 10 that detects the accelerator pedal depression amount APO is input.
Here, the yaw rate φ represents the actual traveling direction of the electric vehicle 1, and therefore the yaw rate sensor 9 corresponds to the actual traveling direction detecting means.

The control unit 6 basically calculates output (torque) target values of the electric motors 2FL, 2FR, 2RL, 2RR based on the accelerator pedal depression amount (accelerator opening) APO and the vehicle speed VSP, and outputs the motor outputs ( Torque) The motor input (voltage) command value corresponding to the target value is output to the motor controller 4FL, 4FR, 4RL, 4RR.
If necessary, these motor output (torque) target values, and hence the motor input (voltage) command values, are corrected as described later.

Therefore, the control unit 6 is as shown in the functional block diagram of FIG. 2 and includes a target yaw rate & each wheel driving force (motor torque) calculation unit 11, a motor input / output coefficient correction & motor input command value calculation unit 12, Consists of.
The target yaw rate & each wheel driving force (motor torque) calculation unit 11 obtains the target yaw rate φ0 from the steering angle θ and the vehicle speed VSP using a vehicle reference model (mathematical model) or the like.
Here, the target yaw rate φ0 represents the target traveling direction of the electric vehicle 1, and therefore the target yaw rate & each wheel driving force (motor torque) calculating unit 11 corresponds to the target traveling direction detecting means.

  The target yaw rate & each wheel driving force (motor torque) calculating unit 11 further controls the accelerator so that the deviation between the target yaw rate φ0 and the detected yaw rate φ is eliminated, that is, the yaw rate φ matches the target yaw rate φ0. Correct the output (torque) target value of each wheel electric motor 2FL, 2FR, 2RL, 2RR obtained from the opening APO and the vehicle speed VSP and correct the motor output (torque) target value T (for each wheel electric motor for convenience) The torque target value is indicated by a common sign).

The motor input / output coefficient correction & motor input command value calculation unit 12 is basically based on the motor input / output characteristic A with a motor input / output coefficient of α illustrated in FIG. Motor input (drive voltage) command value V of each wheel electric motor 2FL, 2FR, 2RL, 2RR for achieving the motor output (torque) target value T from the motor torque calculation unit 11 (for each wheel electric motor for convenience) Drive voltage command values are indicated by a common code), and these are supplied to the corresponding motor controllers 4FL, 4FR, 4RL, 4RR, and the electric motors 2FL, 2FR, 2RL, 2RR are output to the above motor outputs. (Torque) Drive to achieve the target value T.
As a result, the electric vehicle 1 can be driven with a predetermined driving force corresponding to the accelerator opening APO and the vehicle speed VSP, and the actual yaw rate φ (actual traveling direction) is made to coincide with the target yaw rate φ0 (target traveling direction). be able to.

By the way, each wheel electric motor 2FL, 2FR, 2RL, 2RR is used to obtain a motor input (drive voltage) command value from a motor output (torque) target value due to variations in motor input / output coefficient α (see FIG. 4). If the motor input / output coefficient is different from the actual one and an accurate torque corresponding to the motor input (drive voltage) command value V cannot be output, this output torque value will deviate greatly from the output target value and drive each wheel. The force cannot be controlled as intended,
If the driving force of the left and right wheels cannot be controlled as intended, the vehicle cannot travel straight or turn according to the driver's steering operation.
If the driving force of the front and rear wheels cannot be controlled as intended, the driving force is not properly distributed between the front and rear wheels, so that the target running performance cannot be achieved, and power consumption is wasted. Or

Therefore, in this embodiment, the motor input / output coefficient correction & motor input command value calculation unit 12 executes the control program shown in FIG. 3 in addition to the above-described operation, so that the above-described problems do not occur. The motor input / output coefficient α (see Fig. 4) used when obtaining the 2FL, 2FR, 2RL, and 2RR motor input (drive voltage) command values is modified as follows.
The control program shown in FIG. 3 is executed while the electric vehicle 1 is placed on a chassis dynamo (a bench test machine) and is run in the motor input / output coefficient correction mode as follows, unlike the normal running mode described above.

First, in step S1 of FIG. 3, the steering angle θ is read, and based on this, it is determined whether or not the driver's intention is approximately straight traveling.
When the steering angle θ is larger than ± 5 °, for example, it is determined that the driver's intention is not straight traveling, the control is returned to the original state, and the vehicle waits until the vehicle travels straight.
If it is recognized that the steering angle θ is, for example, within ± 5 °, the process proceeds to step S2 with the intention of substantially straight traveling.
In step S2, the electric vehicle 1 is caused to travel by driving the front wheels only by the electric motors 2FL and 2FR without driving the rear wheels.

In the next step S3, it is checked from the yaw rate φ detected by the yaw rate sensor 9 whether the electric vehicle 1 is going straight or turning, and if it is turning, whether it is turning left or right.
When the electric vehicle 1 is turning left or right, in step S4 or step S5, the difference in driving force between the left and right front wheels that causes the turning, that is, the output torque difference Tm between the electric motors 2FL and 2FR is expressed as follows. (1).
Tm = (dφ / dt) · J · Rf / (Lf / 2) (1)
Here, J is the inertia ratio around the vehicle center of gravity, Lf is the front wheel tread, and Rf is the front tire dynamic radius.
Thus, when the output torque difference Tm between the electric motors 2FL and 2FR is obtained by calculation, a sensor for detecting the respective torques is unnecessary, which is advantageous in terms of cost.

  After obtaining the driving force difference (motor output torque difference) Tm between the left and right front wheels in step S4 or step S5, the motor input / output coefficient is corrected as follows.

In the case of a left turn, in step S6 corresponding to the motor input / output coefficient correcting means, the vehicle turns under the current motor input command value (for example, V0 in FIG. 4) (when the left and right front wheel driving force difference Tm is calculated). The motor driving force related to the left front wheel of the inner wheel in the direction is increased from the driving force T1 corresponding to V0 in FIG. 4 by half Tm / 2 of the difference in driving force between the left and right wheels. The motor input / output coefficients β and γ are calculated so that the driving force is reduced by a half Tm / 2 of the left and right wheel driving force difference from the driving force T1 corresponding to V0 in FIG. 4, and these are obtained as the left front wheel driving electric motor 2FL. And the corrected motor input / output coefficient for the right front wheel drive electric motor 2FR.
Thereafter, the motor input / output characteristics B and C corresponding to the corrected motor input / output coefficients β and γ are shown as motor input / output characteristics of the left front wheel drive electric motor 2FL and the right front wheel drive electric motor 2FR, respectively. 4 is used instead of the motor input / output characteristic A, and based on these, the motor input command values of the left front wheel driving electric motor 2FL and the right front wheel driving electric motor 2FR corresponding to the motor output target value T1 are V1 and V2. Asking.

On the other hand, in the case of a right turn, in step S7 corresponding to the motor input / output coefficient correcting means, the current motor input command value (for example, V0 in FIG. 4) (when the left and right front wheel driving force difference Tm is calculated) is obtained. The motor driving force related to the right front wheel of the vehicle turning direction inner wheel is increased by a half Tm / 2 of the left and right wheel driving force difference from the driving force T1 corresponding to V0 in FIG. The motor input / output coefficients β and γ are calculated so that the motor drive force related to the motor drive force T1 corresponding to V0 in FIG. 4 is reduced by half Tm / 2 of the left and right wheel drive force difference. The corrected motor input / output coefficients for the electric motor 2FR and the left front wheel drive electric motor 2FL are used.
Thereafter, the motor input / output characteristics B and C corresponding to the corrected motor input / output coefficients β and γ are respectively shown as the motor input / output characteristics of the right front wheel driving electric motor 2FR and the left front wheel driving electric motor 2FL. 4 is used instead of the motor input / output characteristics A, and based on these, the motor input command values of the right front wheel drive electric motor 2FR and the left front wheel drive electric motor 2FL corresponding to the motor output target value T1 are V1 and V2. Asking.

As described above, the input / output coefficient (input / output characteristics) of the left and right front wheel electric motors 2FL and 2FR is corrected. Used to determine the motor input command value of the left and right wheel electric motor corresponding to the motor output target value T1 through correcting the turning behavior caused by the difference in driving force between the left and right wheels due to the difference in input and output coefficients. The input / output characteristics are close to the actual input / output characteristics such as A, B, and C, and the motor input command values for the left and right front wheels are made like V1 and V2, thereby controlling the driving force for the left and right front wheels to the same T1. In addition, at the time of the straight traveling command, the vehicle can be caused to travel straight according to the command.
On the other hand, since the driving force of the left and right front wheels can be controlled as described above, the electric vehicle can be turned according to the steering operation while the driver commands turning.

After correcting the input / output coefficients (input / output characteristics) of the left and right front wheel electric motors 2FL and 2FR described above, the input / output coefficients (input / output characteristics) of the left and right rear wheel electric motors 2RL and 2RR are calculated in the same manner as follows. Make corrections.
That is, in step S8, the electric vehicle 1 is caused to travel by driving the rear wheels only by the electric motors 2RL and 2RR without driving the front wheels.
In the next step S9, it is checked from the yaw rate φ whether the electric vehicle 1 is going straight or turning, and if it is turning, whether it is turning left or right.
When the electric vehicle 1 is turning left or right, in step S10 or step S11, the difference in driving force between the left and right rear wheels that causes the turning, that is, the output torque difference Tm between the electric motors 2RL and 2RR, It calculates with the following formula | equation (2).
Tm = (dφ / dt) ・ J ・ Rr / (Lr / 2) (2)
Here, J is the inertia ratio around the vehicle center of gravity, Lr is the rear wheel tread, and Rr is the rear tire dynamic radius.
Thus, when the output torque difference Tm between the electric motors 2RL and 2RR is obtained by calculation, a sensor for detecting the respective torques is unnecessary, which is advantageous in terms of cost.

  Thus, after obtaining the driving force difference (motor output torque difference) Tm between the left and right rear wheels in step S10 or step S11, in the case of left turn, in step S12 corresponding to the motor input / output coefficient correcting means, in step S6. Based on the same concept as above, the motor driving force related to the left rear wheel, which is the inner wheel in the vehicle turning direction, is calculated based on the current motor input command value (when the left and right rear wheel driving force difference Tm is calculated). The left rear wheel has a motor input / output coefficient that is increased by half Tm / 2 of the difference, and the motor driving force related to the right rear wheel that is the outer wheel in the vehicle turning direction is reduced by half Tm / 2 of the left and right wheel driving force difference. The corrected motor input / output coefficients for the driving electric motor 2RL and the right rear wheel driving electric motor 2RR are used.

  Thereafter, the motor input / output characteristics corresponding to these corrected motor input / output coefficients are used as the motor input / output characteristics of the left rear wheel drive electric motor 2RL and the right rear wheel drive electric motor 2RR, respectively. In addition, motor input command values for the left rear wheel driving electric motor 2RL and the right rear wheel driving electric motor 2RR corresponding to the motor output target value are obtained and output.

  In the case of a right turn, in step S13 corresponding to the motor input / output coefficient correction means, the current motor input command value (when the left and right rear wheel driving force difference Tm is calculated) is calculated in the same way as in step S7. The motor driving force related to the right rear wheel, which is the inner wheel in the vehicle turning direction, is increased by half Tm / 2 of the difference between the left and right wheel driving force, and the motor driving force related to the left rear wheel, which is the outer wheel in the vehicle turning direction, is increased. The motor input / output coefficients that are reduced by half Tm / 2 of the driving force difference are obtained, and these are the corrected motor input / output coefficients for the right rear wheel driving electric motor 2RR and the left rear wheel driving electric motor 2RL. To do.

  Thereafter, the motor input / output characteristics corresponding to the corrected motor input / output coefficients are used as the motor input / output characteristics of the right rear wheel drive electric motor 2RR and the left rear wheel drive electric motor 2RL, respectively. In addition, motor input command values of the right rear wheel driving electric motor 2RR and the left rear wheel driving electric motor 2RL corresponding to the motor output target value are obtained and output.

As described above, correcting the input / output coefficients (input / output characteristics) of the left and right rear wheel electric motors 2RL and 2RR means that the electric vehicle is driven by the left and right rear wheel When finding the motor input command value of the left and right wheel electric motor corresponding to the motor output target value through correcting the turning behavior caused by the difference in the left and right wheel driving force due to the difference in motor input / output coefficient The input / output characteristics to be used can be made closer to the actual input / output characteristics to control the driving force of the left and right front wheels in the same manner, and the vehicle can be driven straight ahead in accordance with the command at the time of the straight travel command.
On the other hand, since the driving force of the left and right rear wheels can be controlled as described above, the electric vehicle can be turned according to the steering operation while the driver commands turning.

After correcting the input / output coefficients (input / output characteristics) of the left and right front wheel electric motors 2FL and 2FR and correcting the input / output coefficients (input / output characteristics) of the left and right rear wheel electric motors 2RL and 2RR, as described above, The motor input / output coefficient (input / output characteristics) is corrected by comparing the motor input (drive voltage) command values between the front and rear wheels under the same straight-forward command as follows.
The correction is performed by comparing the motor input (drive voltage) command value between the left and right front wheels and the rear wheel, and by comparing the motor input (drive voltage) command value between the other front wheel and the rear wheel. It will be
Here, in particular, the comparison of the motor input (drive voltage) command value between the left front and rear wheels and the comparison of the motor input (drive voltage) command value between the right front and rear wheels, The input / output coefficient (input / output characteristics) will be corrected.
Therefore, for the sake of simplicity, the following description will be made only on the front wheels and on the rear wheels, without mentioning which of the left and right wheels is concerned.

First, in step S14, a constant speed traveling is commanded to travel while keeping the vehicle speed VSP constant under the same traveling conditions.
In the next step S15 corresponding to the front wheel drive constant speed traveling means, the output (torque) target value Tf of the corresponding front wheel electric motor is determined so that this constant speed traveling is performed by the front wheel drive, and this motor torque target value is determined. The front wheel electric motor input (drive voltage) command value Vf for generating Tf is obtained based on the motor input / output characteristics corrected in steps S6, 7 and steps S12, 13 and is output and stored.
In the next step S16 corresponding to the rear wheel drive constant speed travel means, the output (torque) target value Tr of the corresponding rear wheel electric motor is determined in order to perform the above constant speed travel by the rear wheel drive. The rear wheel electric motor input (drive voltage) command value Vr for generating the motor torque target value Tr is obtained and output based on the motor input / output characteristics corrected in steps S6, S7 and S12, 13. Remember.

To add a case where the motor input / output characteristics corrected in steps S6, 7 and steps S12, 13 are like a D characteristic having an input / output coefficient δ as illustrated in FIG. The constant speed travel input (drive voltage) command value Vf and the rear wheel electric motor constant speed travel input (drive voltage) command value Vr are based on the motor input / output characteristics D and output at the constant speed travel of the front wheel electric motor. The (torque) target value Tf and the rear wheel electric motor output (torque) target value Tr during constant speed running are obtained as shown in FIG.
By the way, since the vehicle is commanded to run substantially straight and is driven at a constant speed under the same conditions, the front wheel electric motor input (drive voltage) command value Vf and the rear wheel electric motor input (drive voltage) command value. Vr should be the same, and nevertheless, as shown in FIG. 5, the constant speed running input (drive voltage) command values Vf and Vr of these front and rear wheel electric motors are different. This means that the input / output coefficients (input / output characteristics) are different and the driving force of the front and rear wheels cannot be controlled as intended.
In this case, there is a problem that the driving force is not distributed between the front and rear wheels as intended by the control, so that the target running performance cannot be realized or the power is wasted.

In the present embodiment, in order to solve this problem, the input / output coefficient (input / output characteristics) of the front and rear wheel electric motors is corrected as follows.
That is, in step S17, the above-mentioned front wheel electric motor output (torque) target value Tf of the front wheel electric motor and the rear wheel electric motor output (torque) target value Tr of the rear wheel electric motor are compared. If they are different, it is determined whether Tf> Tr, or conversely, Tf <Tr.

When it is determined in step S17 that Tf> Tr, a difference Tn = Tf−Tr between the two is calculated in step S18, and in the next step S19 corresponding to the motor input / output coefficient recorrecting means, the front and rear wheel electric motors are determined. Under the high-speed driving input (drive voltage) command values Vf and Vr, the constant-speed driving output (torque) target value Tf of the front wheel electric motor corresponding to the larger Vf as shown in FIG. 5 is only Tn / 2. The input / output coefficient of the front-wheel electric motor is changed from δ to ε so that the output (torque) target value Tr at constant speed of the rear-wheel electric motor corresponding to the smaller Vr is increased by Tn / 2. Then, the input / output coefficient of the rear wheel electric motor is corrected again from δ to η.
Thus, the input / output characteristic of the front wheel electric motor is changed from the characteristic D to E in FIG. 5, and the input / output characteristic of the rear wheel electric motor is changed from the characteristic D to F. Thereafter, the motor output is based on these characteristics. The motor input (drive voltage) command value V is obtained from the (torque) target value T and output.

When it is determined in step S17 that Tf <Tr, a difference Tn = Tr−Tf between the two is calculated in step S20, and in the next step S21 corresponding to the motor input / output coefficient recorrecting means, the front and rear wheel electric motors are determined. Under the high speed driving input (drive voltage) command values Vf and Vr, the constant speed driving output (torque) target value Tr of the rear wheel electric motor corresponding to the larger Vr as shown in FIG. The rear wheel electric motor input / output coefficient is changed from δ to ε so that the constant speed running output (torque) target value Tf of the front wheel electric motor corresponding to the smaller Vf is increased by Tn / 2. In addition, the input / output coefficient of the front wheel electric motor is corrected again from δ to η.
Thus, the input / output characteristic of the rear wheel electric motor is changed from characteristic D to E in FIG. 5, and the input / output characteristic of the front wheel electric motor is changed from characteristic D to F. Thereafter, the motor output is based on these characteristics. The motor input (drive voltage) command value V is obtained from the (torque) target value T and output.

  As described above, re-correcting the input / output coefficient (input / output characteristics) of the front and rear wheel electric motors means that the driver commands the vehicle to go straight through the steering wheel and is running at a constant speed under the same conditions. The motor output target leads to correcting the driving performance difference between the front and rear wheels due to the difference in the input / output coefficients of the front and rear wheel electric motors and sacrificing the running performance and wasted power consumption. The input / output characteristics used when obtaining the motor input command values of the front and rear wheel electric motors corresponding to the values are approximated to the actual input / output characteristics as shown in D to E and F of FIG. (Vr), Vr (Vf), and so on, the driving force of the front and rear wheels can be controlled to the same T2, so that the driving performance can be achieved as intended and wasteful consumption of electric power is minimized. be able to.

  In the above, when the electric motor input / output coefficient (input / output characteristics) used when obtaining the motor input (drive voltage) command value from the motor output (torque) target value is corrected so as to approximate it as described above, Since this is done only while the driver intends to go straight ahead, there is no need to consider the difference in motor driving force accompanying steering, and the correction can be performed relatively easily. This is very advantageous in terms of time and cost.

1 is a schematic plan view showing a four-wheel independent drive electric vehicle including a motor input / output coefficient correction device according to an embodiment of the present invention together with its drive system. It is a block diagram according to function of the control unit which comprises the motor input / output coefficient correction apparatus. It is a flowchart which shows the control program which the motor input / output coefficient correction apparatus performs. It is a motor input / output characteristic figure for demonstrating the point at the time of correcting a motor input / output coefficient between right-and-left wheel electric motors in the control program. It is a motor input / output characteristic figure for demonstrating the point at the time of correcting a motor input / output coefficient between front-and-rear wheel electric motors in the control program.

Explanation of symbols

1 Electric car (body)
2FL Electric motor for left front wheel
2FR Electric motor for front right wheel
2RL Left rear wheel electric motor
2RR Electric motor for right rear wheel 3 Battery for electric motor
4FL Motor controller for left front wheel electric motor
4FR Motor controller for right front wheel electric motor
4RL Motor controller for left rear wheel electric motor
4RR Motor controller for right rear wheel electric motor 5 Control unit 6 Steering wheel 7 Steering angle sensor 8 Vehicle speed sensor 9 Yaw rate sensor
10 Accelerator position sensor
11 Target yaw rate & each wheel driving force (motor torque) target value calculator
12 Motor input / output coefficient correction & motor input command value calculator

Claims (11)

The left and right wheels are independently driven by individual electric motors, and the input command values of these electric motors are determined from the output target values according to the planned motor input / output coefficients between these input command values and output target values. In wheel independent drive electric car,
Target traveling direction detection means for detecting the target traveling direction of the vehicle from the steering direction input to the steering means of the wheel independent drive electric vehicle;
An actual traveling direction detection means for detecting an actual traveling direction of the wheel independent drive electric vehicle;
A wheel independent drive electric vehicle comprising: motor input / output coefficient correction means for correcting the scheduled motor input / output coefficient so that the actual traveling direction approaches the target traveling direction based on the detection results by these means. Motor input / output coefficient correction device. In the motor input / output coefficient correction device according to claim 1,
The motor input / output coefficient correction of the wheel independent drive electric vehicle characterized in that the motor input / output coefficient is corrected when the target travel direction of the vehicle detected by the target travel direction detecting means is substantially straight. apparatus. In the motor input / output coefficient correction device according to claim 2,
The motor input / output coefficient correcting means calculates a driving force difference between the left and right wheels from the actual traveling direction of the electric vehicle detected by the actual traveling direction detecting means, and the left and right wheels so as to eliminate the left and right wheel driving force difference. A motor input / output coefficient correction device for a wheel-independent drive electric vehicle, wherein the motor input / output coefficient is corrected. In the motor input / output coefficient correction device according to claim 3,
The motor input / output coefficient correcting means increases the motor driving force related to the vehicle turning direction inner wheel by half of the left / right wheel driving force difference based on the input command value when the left / right wheel driving force difference is calculated, The motor input / output coefficient that reduces the motor driving force related to the outer wheel in the vehicle turning direction by half the difference between the left and right wheel driving force is used as the corrected motor input / output coefficient. Output coefficient correction device. In the motor input / output coefficient correction device according to any one of claims 1 to 4,
A motor input / output coefficient correction apparatus for a wheel-independent drive electric vehicle characterized in that the motor input / output coefficient is corrected individually for left and right front wheels and left and right rear wheels. Front and rear wheels are driven independently by individual electric motors, and the input command value of each electric motor is determined from the output target value according to the expected motor input / output coefficient between these input command value and output target value. In wheel independent drive electric car,
Front wheel drive constant speed traveling means for traveling the wheel independent drive electric vehicle at a constant speed by front wheel drive;
Rear wheel drive constant speed traveling means for causing the wheel independent drive electric vehicle to travel at a constant speed by rear wheel drive under the same conditions and at the same speed;
Based on the front wheel electric motor input command value during constant speed traveling and the rear wheel electric motor input command value during constant speed traveling during front wheel driving constant speed traveling and rear wheel driving constant speed traveling by these means, the front wheel electric motor output target The planned motor input / output coefficient is corrected so that the value and the rear wheel electric motor output target value are between the front wheel electric motor output target value and the rear wheel electric motor output target value based on the planned motor input / output coefficient, respectively. A motor input / output coefficient correction device for a wheel-independent drive electric vehicle characterized by comprising motor input / output coefficient correction means. In the motor input / output coefficient correction device according to claim 6,
A wheel independent drive electric vehicle characterized in that a value between a front wheel electric motor output target value and a rear wheel electric motor output target value based on the predetermined motor input / output coefficient is an intermediate value between these motor output target values. Motor input / output coefficient correction device. In the motor input / output coefficient correction device according to claim 6 or 7,
A motor input / output coefficient correction device for a wheel-independent drive electric vehicle, wherein the motor input / output coefficient is corrected when the electric vehicle is running substantially straight. For both the front and rear wheels, the left and right wheels are independently driven by the individual electric motors, and the input command values of these electric motors are determined from the output target values according to the expected motor input / output coefficients between these input command values and the output target values. The motor input / output coefficient correction device according to claim 1, wherein the motor input / output coefficient correction device is used for a wheel independent drive electric vehicle.
Front wheel drive constant speed traveling means for traveling the wheel independent drive electric vehicle at a constant speed by front wheel drive by an electric motor controlled based on the corrected motor input / output coefficient;
Rear wheel drive constant speed running means for running the wheel independent drive electric vehicle at a constant speed at the same speed under the same conditions by a rear wheel drive by an electric motor controlled based on the corrected motor input / output coefficient;
Based on the front wheel electric motor input command value during constant speed traveling and the rear wheel electric motor input command value during constant speed traveling during front wheel driving constant speed traveling and rear wheel driving constant speed traveling by these means, the front wheel electric motor output target The corrected motor input / output coefficient is again set so that the value and the rear wheel electric motor output target value are between the front wheel electric motor output target value and the rear wheel electric motor output target value based on the corrected motor input / output coefficient. A motor input / output coefficient correction device for a wheel-independent drive electric vehicle, comprising: a motor input / output coefficient re-correction means for correcting. In the motor input / output coefficient correction device according to claim 9,
A wheel independent drive electric vehicle characterized in that a value between a front wheel electric motor output target value and a rear wheel electric motor output target value based on the corrected motor input / output coefficient is an intermediate value between these motor output target values. Motor input / output coefficient correction device. In the motor input / output coefficient correction device according to claim 9 or 10,
A motor input / output coefficient correction device for a wheel-independent drive electric vehicle, wherein the motor input / output coefficient is corrected again when the electric vehicle is running substantially straight.

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